1. Technical Field
The present invention relates to a print apparatus and a print method with which ink is ejected and halftone dots are printed.
2. Related Art
A print apparatus prints halftone dots corresponding to a predetermined image by ejecting ink from a print head. Herein, a “halftone” refers to an image constituted of dots that have different screen rulings, sizes, shapes, or densities. A halftone is generated by dithering, error diffusion, and the like. “Halftone dots” refers to the individual elements that constitute the tone. Halftone dots can have a variety of shapes, such as square, round, or elliptical. Halftone dots are also referred to as simply “dots” below.
In some instances, in the process of ejecting the ink, the ink separates into main droplets and satellites. In such an instance, the satellites may in some cases make impact and form dots at positions different from those of the main droplets. For this reason, in some instances the coverage rate, which is the proportion of printing substrate that is covered, may fluctuate due to the satellites, causing the image quality to be degraded. In recent years, a dispersed arrangement pattern of dots, where the dots are arranged in a dispersed manner, has become a standard practice, and the degradation of image quality caused by the satellites has a considerable impact.
There has therefore been disclosed a print apparatus for overlaying other dots onto the satellites by arranging the dots continuously in a main scan direction that intersects with a direction of feeding of the printing substrate. With such a print apparatus, the fluctuations in the coverage rate are curbed by having the satellites be overlaid onto the other dots. As a result, the degradation of image quality for the printed article can be reduced (for example, see Japanese Laid-open Patent Publication 2007-168202).
Causing many dots to overlap, as per the invention illustrated in the aforementioned Japanese Laid-open Patent Publication 2007-168202, does make it possible to obscure the satellites. New problems arise, however, in that the overlaid dots appear as a single lump of dots, or in that bleeding of the ink becomes readily apparent.